Review of Mary S . Morgan ’ s The world in the model : how economists work and think . Cambridge University

The world in the model is a distillation of fifteen years of concentrated work by a major philosopher and historian of economics. Mary Morgan's topic is how economists use models. Her aim is " to offer both a history of the naturalization of modelling in economics and a naturalized philosophy of science for economics ". Recognising that " science is messy " , she presents " a series of historical case studies through which the philosophical commentary runs ". She describes this commentary as an account of modelling " as a way of doing science that has its own rationale just as do other modes of science " (pp. xv-xvi). This is a long book, written with great clarity and rich in historical detail. The opening chapter, which sets out the agenda for the rest of the book, includes discussions of Quesnay's Tableau Economique, arguably the first economic model, and of Frisch's model of macroeconomic cycles. The following chapters link methodological themes with extended historical studies of modelling practice. These studies feature Ricardo's model of the distribution of the economic product, the Edgeworth Box, the concept of the rational economic man, the Newlyn-Phillips Machine, the IS–LM model, the supply and demand diagram, and the Prisoner's Dilemma. As a practising economic modeller with only limited knowledge of the history of economics, I found the case studies fascinating and illuminating. I particularly enjoyed Morgan's accounts of David Ricardo and of the Newlyn-Phillips Machine. In conventional histories of economic thought, Ricardo is often presented as the first formal economic theorist. His approach is seen as substituting dry but mathematically tractable abstractions in place of Adam Smith's wide-ranging interest in actual economic life. His style of reasoning—working through numerical examples rather than general qualitative relationships—is seen as clumsy, or perhaps as a necessary concession to his readers' lack of mathematical sophistication. Morgan